# 1000 Dateien, Datei-Nr. 999 ist nicht lesbar:
$ perl bench.pl 
       Rate eval sub1 sub2  all
eval  523/s   -- -60% -61% -64%   # using eval and join
sub1 1318/s 152%   --  -1%  -9%   # sub with addition
sub2 1330/s 154%   1%   --  -8%   # sub with direct return from loop
all  1450/s 177%  10%   9%   --   # sub with usage of List::MoreUtils::all

# 2000 Dateien, Datei-Nr. 999 ist nicht lesbar:
$ perl bench.pl 
       Rate eval sub1 sub2  all
eval  243/s   -- -61% -81% -83%
sub1  620/s 155%   -- -53% -57%
sub2 1309/s 438% 111%   -- -10%
all  1450/s 496% 134%  11%   --

# 10 Dateien, alle lesbar
$ perl bench.pl 
         Rate eval sub1 sub2  all
eval  35485/s   -- -68% -68% -72%
sub1 111348/s 214%   --  -1% -11%
sub2 112439/s 217%   1%   -- -11%
all  125754/s 254%  13%  12%   --

# 10 Dateien, Datei-Nr. 7 nicht lesbar
$ perl bench.pl 
         Rate eval sub1 sub2  all
eval  36202/s   -- -67% -78% -79%
sub1 108687/s 200%   -- -33% -38%
sub2 162293/s 348%  49%   --  -7%
all  174121/s 381%  60%   7%   --